Disk drives comprise a disk and a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and servo sectors. The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system to control the velocity of the actuator arm as it seeks from track to track.
FIG. 1 shows a prior art disk format 2 as comprising a number of data tracks 6 defined by servo sectors 40-4N recorded around the circumference of each data track. Each servo sector 4, comprises a preamble 8 for storing a periodic pattern, which allows proper gain adjustment and timing synchronization of the read signal, and a sync mark 10 for storing a special pattern used to symbol synchronize to a servo data field 12. The servo data field 12 stores coarse head positioning information, such as a track address, used to position the head over a target data track during a seek operation. Each servo sector 4, further comprises groups of servo bursts 14 (e.g., A, B, C and D bursts), which comprise a number of consecutive transitions recorded at precise intervals and offsets with respect to a data track centerline. The groups of servo bursts 14 provide fine head position information used for centerline tracking while accessing a data track during write/read operations.
When a disk drive is installed into a host computer (e.g., a personal computer), an operating system (OS) is normally loaded onto the disk, after which the host computer may boot from the disk drive. Due to the mechanical latency of the disk drive (the seek latency of the actuator arm and the rotational latency of the disk) the boot operation may be undesirably long. In addition, if the disk is accessed non-sequentially when reading the operating system, the boot operation may take even longer due to the head seeking to target tracks and waiting to reach target data sectors.
There is, therefore, a need for a disk drive which helps expedite the boot operation for a host computer.